1. Field of the Invention
This invention relates to an impact sensor capable of detecting an impact direction, which is suitably used for a car air bag for protecting an occupant from impact due to a car clash, and also relates to an impact sensor suitable for a clash recording device which is capable of recording a clash situation when a car is damaged in a car clash.
2. Related Art
There has been recently propagated a car in which an air bag for protecting occupants such as a driver and so on from impact is installed. The air bag is so designed as to be inflated at the instantaneous time when the car suffers an impact which would damage an occupant body, and thus its operation is greatly dependent on performance of a sensor for detecting the impact. All impact sensors which have been hitherto developed are so designed as to detect an impact in a traveling-direction of a car, which includes a longitudinal (long-axial) direction of the car and a direction within 30 degrees at a left or right side with respect to the longitudinal direction.
Accordingly, a conventional impact sensor can not accurately detect the impact strength and impact direction of a car clash in a width (short-axial) direction of the car or in any direction of other arbitrary angle. This restriction in the detection accuracy is caused by the restriction in an installing position of the air bag, that is, because the installing position of the air bag is restricted to an handle or a front panel. However, it is expected that in the near future an air bag will be installed at a side of the car to protect the occupant from a car clash in the side direction of the car, and thus it is clear that an impact sensor capable of sensing an impact in all directions; that is, an omnidirectional impact sensor; will be required.